Brian K. Gehlbach, MD, Assistant Professor of Medicine in the Section of Pulmonary and Critical Care at the University of Chicago, seeks support for research career development to establish a career as a clinical investigator with a focus on disturbances of sleep and circadian rhythmicity in critically ill patients. Dr. Gehlbach will develop his research skills under the mentorship of Dr. Eve Van Cauter, a well-known authority on sleep and circadian rhythms in normal and pathologic states. He will be co-mentored by Dr. Jesse Hall, an accomplished investigator in the critically ill and an authority on the sedation of mechanically ventilated patients. Dr. Jean-Paul Spire, an expert neurophysiologist and Director of the Sleep Fellowship Program, will provide additional mentoring where interpretation of the polysomnograms is concerned. In addition, Dr. Gehlbach will enroll in the certificate program sponsored by the university's NIH-funded Clinical Research Training Program. The proposed research project is designed to characterize sleep and circadian rhythmicity in critically patients and to explore the efficacy of a non-pharmacological intervention. The specific aims of the proposal are to characterize the quantity and quality of sleep in critically ill patients undergoing mechanical ventilation, to examine the effect of a protocol employing noise reduction and enforcement of a robust light-dark cycle on sleep quality and circadian rhythmicity, and to examine the relationship between sleep disruption and loss of circadian rhythmicity and the development of delirium. Sleep will be analyzed through the use of continuous polysomnography and circadian rhythmicity will be characterized through the measurement of core body temperature and urinary hormonal levels at frequent intervals. Over 1 million patients develop respiratory failure annually in the United States; yet, the sleep of patients undergoing mechanical ventilation has received little attention. The goal of this project is to improve the sleep and circadian rhythms of critically ill patients through practical strategies that can be employed at the bedside. Increased attention to sleep quality may improve clinical outcomes by reducing the development of delirium and helping patients recover from respiratory failure. [unreadable] (End of Abstract) [unreadable] [unreadable] [unreadable]